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LDV
LDV 1 Limiting descent velocity.
2 Laser Doppler velocimeter.
3 Local Defence Volunteers [1940, in 1941 became
Home Guard] (UK).
ldw Landing weight.
LE 1 Leading edge; now has confusing additional
meaning arising from expression ‘* of technology’,
signifying the very latest advances into unknown fields.
2 Life extension.
3 Link establish[ed].
Le Lewis number.
LEA Leurre [lure] electromagnétique actif (F).
LEAA Law-Enforcement Assistance Administration
(US).
lead 1 Angular measurement of many variables (eg
crankshaft motion between opening of exhaust value and
TDC, or AC vectors related to zero-lead reference).
2 Angular distance between sightline to moving target
and direction of aim to hit it.
3 First aircraft in element, or first element in large
formation.
4 Dominant member of formation aerobatic display
duo or team; role is to fly sequence precisely, without
looking at No 2.
5 Different pronunciation, Pb, soft ductile metal,
density 11.4, MPt 334°C.
lead aircraft 1 Aircraft with greater flight time than any
other of similar type or using similar airframe.
2 Obviously, that leading a formation or group; see
leadplane.
lead angle See lead (2).
lead azide Explosive triggered by mechanical deformation,
used in detonators.
lead-computing sight Gyro or other sight sensitive to
flight manoeuvres and providing a direct aiming mark to
be superimposed over the target.
leaded fuel Containing small percentage TEL as antiknock
additive.
leader cable Electrically conductive cable buried along
centreline of runway and taxiway to provide ground guidance
in zero visibility.
lead-in 1 Formerly ground facilities and features
between outer marker and threshold.
2 Tube through which aerial or towed MAD bird cable
enters aircraft.
lead-in fighter Advanced jet trainer with which pupil can
practise fighter missions, with sensors and weapons.
leading Angular displacement ahead of normal rest
position of main-rotor blade of rotory-wing aircraft.
leading edge 1 Front edge of wing, rotor, tail or other
aerofoil. Not precisely defined and, especially when made
as detachable unit, extends to rear of 0% chord.
2 Rising slope of electronic pulse, esp. one on precise
timebase, as in CRT, IFF, video etc.
3 Frontier of knowledge (see comment under LE).
leading-edge flap Any hinged high-lift surface attached
to the leading edge but not forming the leading edge itself
(ie, not a droop).
leading-edge radiator Piston-engine radiator incorporated
into wing ahead of front spar.
leading-edge root extension Sharp increase of wing
chord at LE root, often almost flat and projecting ahead
of wing profile proper, to cause strong vortex at high
LEAP
AOA and enhance lift, control and manoeuvrability. In
extreme (long-chord form) becomes a large strake.
leading-edge sweep Angle between local (or, sometimes,
mean) leading edge and OY axis.
leading panel The FSW in an oblique [slew] wing
aircraft.
leading sweep Curvature of propeller blade towards
leading edge [rare-after 1914].
lead/lag axis The quasi-vertical axis at or near the root
of a helicopter rotor blade about which the blade can
pivot forward or lag to the rear.
leadplane That guiding fire tankers to the retardant
drop zone, orders sequence and approach path, watches
for conflicts and relays altimeter setting (USFS).
lead pole Connects cable to tow banner.
lead-pursuit Traditional air-to-air attack using fixed
guns, approach from rear and aiming ahead of crossing
target.
lead-replacement petrol UK term for piston engine gasolines
in which lead is replaced by VSR additives; in 2002
not yet approved for aviation.
LEADS, Leads Law-enforcement agencies data system
(airport com. systems).
lead ship Prominently marked aircraft on which large
day bomber formations formed up before setting course.
lead time Time between (a) placing order for bought-out
item, or (b) starting fabrication of major airframe part or
even (c) receiving heavy plate or other raw material, and
emergence of finished aircraft. Expression also, incorrectly,
used for time between ordering aircraft and its
delivery.
leaf brake Power tool for making radiused straight
bends in sheet.
leaf seal Air or gas seal comprising a dense ring of thin
foil blades, sloping in the direction of rotation,
surrounding a shaft.
leakage Loss of aerostat gas.
leakage drag That due to local flows between fixed [eg,
wing, tailplane] and movable parts of aircraft.
leaky turbojet Turbofan of very low BPR (under 0.5).
lean 1 Of fuel/air mixture, below stoichiometric, lacking
fuel.
2 Linear distance at tip between position of backwardsleaning
rotor blade (usually of gas-turbine compressor or
helicopter) and position it would occupy if truly radial; the
lean is sometimes along the tip-path plane and sometimes
along chord line at tip.
Lean Aerospace Initiative Programme by the SBAC and
six UK universities to adapt the best practices in lean tools
and processes (Toyota) to the aerospace industry. A
major difference is that, unlike the motor industry, aerospace
involves a great deal of non-recurring activity.
lean manufacturing Keeping production line flowing
with smallest possible inventory of components and work
in progress, and elimination of muda [waste]. (pioneered
by Toyota).
lean mixture octane At present this means fuel with TEL
giving octane rating of 100. Essential for supercharged
piston engine engines, replacements for TEL are being
sought.
Leans (the) Vertigo.
LEAP 1 Lightweight exo-atmospheric projectile.
2 Leading-edge aviation propulsion.
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